2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Porting Boundaries

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Old Jun 11, 2009 | 01:01 PM
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Justen's Avatar
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Porting Boundaries

I'm doing my own backyard rebuild, on my first rotary. I'm in the process of porting my end plates and mid iron. Mild streetport from pineapple racing.
I know how spreading the intake opening in different directions affects the timing and power band and such...

What i want to know is how much room for error do you have and the inside edge of the port (closest to the e-shaft) without leaking oil? .... Cuz i nicked that edge and had to sand it out a little but not much.

Any one have any pictures of port jobs that caused an oil leak?
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Old Jun 11, 2009 | 01:23 PM
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Take a oil ring and put it where it would ride along on the iron. If you went underneath it, its going to leak.
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Old Jun 11, 2009 | 01:42 PM
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Don't port that direction at all.
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Old Jun 11, 2009 | 02:46 PM
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I understand that i'm not supposed to port in that direction at all. I nicked that side accidentally.

I'm assuming you mean to run the seal along the circular wear marks?
I tried it and only the outside edge of the seal hangs over ever so slightly, but shouldn't it be okay? ...Considering the inside diameter of the seal does not cross over into the port area?
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Old Jun 11, 2009 | 03:04 PM
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Might want to take a pic. But from my experience, you don't want to go under that area AT ALL. When porting, you go outward (in the direction of the intake) and up.
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Old Jun 12, 2009 | 05:00 AM
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You can actually see the area where the oil control ring rides. The gap between the oil control ring trajectory and the inner surface of the port is around 1mm or .040". If you compromise that at all, you need to measure the end result. Using a caliper, measure the radial width of the band defined by the center hole in the iron and the inner surface of the port. Take this measurement on an uncompromised iron and the point where you nicked yours. That will tell you how much you've affected it by.
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